14. Tortoise and Rabbit Race10000m, the speed of the rabbit is five times that of the tortoise. When they started from the starting point together, the tortoise kept running, and the rabbit ran somewhere and began to sleep. When the rabbit woke up, the turtle was 5000 meters in front of it, and the rabbit caught up, but when the turtle reached the finish line, the rabbit was still behind 100 meters. How many meters did the tortoise run while sleeping?
15. Two cars, A and B, set off from A and B respectively, heading in opposite directions, and met four hours later. After the encounter, car A continued to drive for 3 hours to reach car B, and car B was driving at a speed of 24 kilometers per hour. What is the distance between AB and b?
16. The distance between the two places is 380 kilometers. There are two cars leaving from two places at the same time. Originally, car A planned to run at 36 kilometers per hour and car B planned to run at 40 kilometers per hour, but when driving, car A changed speed and left at 40 kilometers per hour. How many kilometers did B car travel less than originally planned when they met?
17. The east and west towns are 240 kilometers apart. There is a bus from Dongzhen to Xizhen at 8: 00 a.m., and a truck from Xizhen to Dongzhen at 9: 00 a.m., and the two cars meet at the midpoint of the two towns at noon 12. If both cars leave at 8: 00 a.m. with the same speed, how many kilometers are the two cars apart by morning 10?
18. The bus and truck leave from Station A and bilibili at the same time, and the speed of the bus is 54 kilometers per hour.
The truck travels 48 kilometers per hour. After the two cars met, they continued to move at the original speed. The bus returned immediately after arriving in bilibili, and the truck returned immediately after arriving at Station A. When the two cars met again, the bus traveled 2 16 kilometers more than the truck. How many kilometers is the distance between the two stops?
19. On the day of "August 1st" Festival, a young pioneer went from school to the PLA barracks 17 kilometers away, with a speed of 4 kilometers per hour. 0.5 hours after the departure, the People's Liberation Army rushed to meet, 2 kilometers faster than the Young Pioneers. How many hours later, they met on the road?
20. The distance between Station A and bilibili is 440 kilometers. A cart and a car leave two stations relatively. The cart travels 35 kilometers per hour and the car travels 45 kilometers per hour. A swallow set out with the cart at a speed of 50 kilometers per hour and flew to the cart. After meeting the cart, it turned back and flew to the cart. When it meets a cart, it flies back to the cart, and so on. How many kilometers did the swallow fly before the two cars met?
2 1. The distance between the two places is1120km, and two trains leave in opposite directions at the same time. The first train travels 60 kilometers per hour and the second train travels 48 kilometers per hour. When the second train left, a pigeon flew out of it and flew to the first train at a speed of 80 kilometers per hour. When the pigeon meets the first train, how far is the second train from its destination?
22. At 8 o'clock in the morning, the two cars drove in the opposite direction from directions A and B, which were 2 10 km apart. The first car stopped for 45 minutes while repairing the car, and the second car stopped for half an hour because of refueling.
We met at 1 1 this morning. If the first car travels 40 kilometers per hour, how many kilometers does the second car travel per hour?
23. Xiaogang and Xiao Yong rode bicycles from two opposite places at the same time. Xiaogang met Xiao Yong in 5/8 of the whole journey. Xiao Yong continued to advance at the speed of 10 km per hour, and ran the rest of the distance in 2.5 hours, seeking Xiao Gang's speed?
24.a and B run back and forth on a straight road 90 kilometers apart. A runs at a speed of 3 meters per second and B runs at a speed of 2 meters per second. If they start at both ends of the straight road at the same time, how many times will * * * meet when they finish running 10 minutes? 25. Two athletes, a man and a woman, practiced running on a slope with a length of 1 10 meter (A is on the top and B is on the bottom). Both of them start from point A at the same time and keep running back and forth between point A and point B. If the male athlete's uphill speed is 3 meters per second and the downhill speed is 5 meters per second; The uphill speed of female athletes is 2 meters per second, and the downhill speed is 3 meters per second. So how many meters away from point A is the place where two people meet head-on for the second time?
0 1, 40 pears are allocated to 3 classes, 20 pears are allocated to 1 class, the rest are allocated to 2 classes and 3 classes equally, and 2 classes are allocated to ().
Seven years ago, Xiao Qiang was six times his son's age. My son is 12 years old and my mother is () years old.
03, the students have a radio exercise competition, and the whole class is arranged in six equal rows. Xiaohong is in the second row. From the beginning, she stands in the fifth position, and from the back, she stands in the third position. There are () people in this class.
There is also a paper! ! !
Sixth grade Olympic mathematics examination paper
I. Calculation (5×5=25 points)
1、4 9 16 25 (36) (49) (64)
2、 1 3 6 10 ( 15) (2 1) (28)
3、2 6 18 54 ( 162) (486) ( 1458)
4、65432 1× 123456-65432 1× 123455=65432 1
5、 1 1 1 1 1× 1 1 1 1 1= 12345432 1
Second, fill in the blanks. (3×25=75 points)
There are (339) natural numbers of 1, and less than 400 without the number 8.
2. Nine copper coins, one of which is fake, and the authenticity is only different in quality. If you weigh it at least (8 times) with a balance without weight, you can definitely find out the fake copper coins.
3. There is a warehouse ***5 warehouses every100km on the highway. Warehouse 1 has 10 tons, warehouse 2 has 20 tons, warehouse 5 has 40 tons, and the other two warehouses are empty. Now I want to put all the goods in one warehouse. If the freight of 1 km per ton of goods needs 1 yuan, then it needs at least (10000) yuan.
1No. 100 km 2 100 km 3 100 km 4 100 km 5.
10 tons, 20 tons and 40 tons
There are 207 students in Grade 6 * *, of whom 2/ 1 1 boys and 7 girls were selected to take part in the math contest. The number of other boys and girls is the same, with 97 girls in grade 6.
5. Xiaolan and Xiaoli play guessing games. Xiaolan writes a four-digit decimal on the straight line for Xiaoli to guess. Xiaoli asked, "Is it 603 1?" Xiaolan said: "I guessed a number, and the location is correct." Xiaoli asked again, "Is it 5672?" Xiaolan said: "I guessed both numbers correctly, and neither position is right." Xiaoli asked again, "Is it 4796?" Xiaolan said, "I guessed four numbers right, but none of them are right." Can you infer the four digits written by Xiaolan from the above information? 6974
6. If 20 rabbits can be exchanged for 2 sheep, 8 sheep for 2 pigs and 8 pigs for 2 cows, how many rabbits can 4 cows be exchanged? 640
7. Light light blue is 8 years old and her father is 38 years old. How old is light light blue? Dad is exactly four times as old as light light blue. 10
8. For the people, every three empty soda bottles can be replaced by 1 bottle. Light light blue bought 99 bottles of soda in the summer vacation, and changed them into empty bottles after drinking them. How many bottles of soda can she drink at most? 147
9. In a division formula, the sum of dividend, divisor, quotient and remainder is 75, the known quotient is 8, and the remainder is 2. What are the dividend and divisor?
58 7
10. There are two iron wires of the same length. The first one is minus 30 cm, the second one is minus 18 cm, and the remaining length of the second one is twice that of the first one. How many centimeters is left in the second wire? 24
There are 1 1, 1, 2, 3, 4, 5, 6, 7, 8 and 9 cards, each with three cards. A said, "The product of my three cards is 48", and B said, "The sum of my three cards is 65438.
238 564 179
/kloc-how many different rectangles can a 0/2.24cm long iron wire enclose (the length and width are all whole centimeters, not counting joints)? What are the areas? Compare it again. What can you find? six
13 Master Zhang is used to taking two days off every five days of work. Recently received the task of producing 330 parts. He produces 30 parts every day. How many days will it take to complete this task? 15
On Sunday, Xiaohui took a taxi to visit her grandmother 8 kilometers away. When taking the bus, he looked at the fare list on the taxi: 8 yuan within 5 kilometers; More than 5 kilometers per kilometer in 2 yuan. How much does Xiaohui have to pay to go to grandma's house?
14
15, a decimal, if you expand its decimal part by 4 times, you will get 5.4; If you enlarge its decimal part by 9 times, you get 8.4. What is this decimal? 3、6
16, average height of Party A and Party B 1.66m, average height of Party B and Party C 1.7m, average height of Party A and Party C 1.65m, what is the average height of Party A, Party B and Party C?
1。 67
17, the sum of a, b and c is 270. A is three times that of B, and B is twice that of C. What are the numbers of A, B and C respectively?
180 60 30
18. There are two coal yards A and B. The coal storage capacity of coal yard A is three times that of coal yard B. If 180 tons is transported from coal yard A to coal yard B, the coal storage capacity of the two coal yards is equal. How many tons are there in coal yard A and coal yard B respectively?
540 180
19, five players line up to do exercises, among which 1 new players can't stand at the head. How many different ways are there?
96
There are 50 students in Class 20.6 (1). There are 25 swimmers, 28 gymnasts and 5 non-gymnasts. How many students can swim and do gymnastics? eight
2 1. It takes 6 hours for the ship "Youth" to sail along the river at 120km, and 20 hours to sail against the current at 280km. How many hours does it take for a ship to sail 340 kilometers in still water?
20
22. Arrange all the simplest false scores with denominator of 15 from small to large, and find the numerator of the 99th false score.
2 14
23. Make a bouquet with 96 red flowers and 72 white flowers. If there are the same number of red flowers and the same number of white flowers in each bouquet, how many flowers are there in each bouquet?
84
2. There are 240 students taking part in large-scale group gymnastics. They stand in a row facing the coach and press 1, 2, 3, 4, ... from left to right. The coach asked each student to remember the number he quoted and do the following actions: first, let the students who quoted a multiple of the number 3 back off, then let the students who quoted a multiple of 5 back off, and finally let the students quote a multiple of 7. 34+80+48- 16-6- 1 1= 162-33= 129
1. The mountain village postman went over the mountains from the post office and took 6.5 hours to deliver the mail to the user's home. His speed up the mountain is 3 kilometers per hour, and his speed down the mountain is 5 kilometers per hour. How long does it take to return at the same speed?
4.7
1.8 8 3 3 Calculate 24 with+-*/().
2.3 3 7 7 Use+-*/() to calculate 24.
3. Bus length190m, truck length 240m. The two cars are traveling at a speed of 20 meters per second and 23 meters per second respectively. How many seconds does it take to meet from front to back on the double-track railway?
An: 10 second.
4. Calculate1234+2341+3412+4123 =?
5. The first item in arithmetic progression is 5.6, and the sixth item is 20.6. Find its fourth project.
6. The sum is 0.1+0.3+0.5+0.7+...+0.87+0.89 =?
7. Coins with 1.2.5 cents * * 100, with a total value of 2 yuan. It is known that the total value of 2-cent coins is more than 1 cent coins 13 cents. How many coins are there in each of the three types?
8. The distance between A and B is 465 kilometers. It takes * * * 7 hours for a car to travel from A to B at a speed of 60km/h, and then speed up 15km/h to arrive at B. How many hours have you been driving at a speed of 60 km/h?
9 .. There are several chickens and rabbits in the cage, which are *** 100 feet. If the chicken is replaced by a rabbit and the rabbit is replaced by a chicken, it will have 92 feet. How many rabbits and chickens are there in the cage?
10. Spiders have eight legs, dragonflies have six legs and two pairs of wings. Cicada has six legs, 1 pair of wings. At present, there are 18 of these three kinds of bugs, with 1 18 legs and 20 pairs of wings. How many bugs are there in each species?
1 1. In the activity of learning from Lei Feng, students * * * did 240 good deeds, senior students each did 8 good deeds, and junior students each did 3 good deeds, with an average of 6 good deeds. How many students are there in this activity?
12. A class of 42 students participated in tree planting, with an average of 3 trees planted by boys and 2 trees planted by girls. It is understood that boys plant 56 more trees than girls. How many boys and girls are there?
13. There are 6 different Chinese books, 4 different foreign language books and 3 different math books on the bookshelf. How many different ways can you get them?
14. Students in one class plant trees, and there are 100 Chinese fir seedlings and poplar seedlings. Each group was divided into 6 Chinese fir seedlings and 8 poplar seedlings. In this way, the Chinese fir seedlings have just been beaten, and there are two poplar seedlings left. How many Chinese fir seedlings and poplar seedlings are there?
15. With 8 kilograms of silk, you can weave silk with a width of 6 centimeters with 4 meters. Now silk has 10kg. How many meters can a 7.5 decimeter wide silk weave?
16. Here is a number of 1 1, and the sum of every three adjacent numbers is 15. Do you know what the question mark means? What's the number of this 1 1?
17 ... Party A, Party B and Party C bought eight loaves and divided them equally. Party A paid five cakes, Party B paid three cakes, and Party C didn't bring any money. After calculation, C should pay 4 yuan, and how much should A take back?
18. Football has five teams: A, B, C, D and E, and each team has to play a game with other teams. How many games are there altogether?
19. 12 total coin value 1 yuan, of which only five cents and 1 minute. How many coins are there?
20. Party A and Party B go to the store to buy clothes. Party A 100 Yuan, Party B 70 yuan. After they bought clothes at the same price, they found that the money left by Party A was exactly four times that of Party B. How much did Party A and Party B spend on clothes?
2 1.57 military vehicles lined up to cross a bridge with a distance of 2m. The bridge is 200 meters long, and each military vehicle is 5 meters long. How many meters is it from the front of the first car to the rear of the last car?
22. Buying 18 table with 6 chairs costs 1560 yuan, and the price of 10 table is more than the price of 6 chairs. 680 yuan, how much is each table? How much is each chair?
23 ..A Two oil storage tanks, A and B, have less oil storage than B. Enter 1/6 1/4 B into A. A has 2 tons more oil storage than B. How many tons does B have?
24. The factory organized 400-450 people to participate in tree planting activities, and each person planted 32 trees on average. Male workers and female workers planted an average of 48 trees and 65,438+03 trees respectively. How many male and female workers took part in planting trees? (Number of people in proportion)
25. Stores A, B and C have 120 pieces of relief materials, which is the sum of warehouses A and C, and C is half of warehouses A and B. How many pieces of relief materials are there?
26 .. A, B and C installed 500 TV sets in three groups. The ratio of the number of TV sets installed in the two groups is 5:3, and C is 39 fewer than B. How many TV sets has C installed? (Suppose there are 39 units left in C)
27. The distance between A and B is 243 kilometers. A van and a bus leave from A and B at the same time, face to face, 1.5 hours later. The speed ratio of truck and bus is 4:5, so how many hours will it take for the bus to complete this journey? (two methods)
28. A daily chemical factory produced 9800 pieces of laundry soap, 5/9 more than the soap produced. How many boxes of laundry soap and soap are produced? (Solving problems skillfully with variable rate)
29. Xiao Ming and Xiao Cong started running back and forth at both ends of the 60-meter runway respectively. Xiao Ming runs 2 meters per second and Xiao Cong runs 3 meters per second. They ran for five minutes. How many times have they met during this period?
Xiao Qiang bought three pencils, three ballpoint pens, eight notebooks and twelve erasers. The salesman said * * * should pay 13 yuan, 1 minute. People know that 2 yuan has a 4-cent pencil and an 8-cent ballpoint pen in his money. He asked the shop assistant if his account was wrong.
3 1. For a project, Party A will work alone for 3 days, and Party B will sit alone for 5 days. Now Party A will do 1 day first, and how many days will the remaining cooperation between Party A and Party B be completed?
32. The rice in warehouse B is 4/5 of that in warehouse A. If 4 tons of rice is transferred from warehouse A to warehouse B, the weight ratio of rice in warehouse A and warehouse B is 3: 4. How many tons of rice were originally stored in warehouse B and warehouse B?
At 33.7: 00, the minute hand lags behind the hour hand by 100 degrees.
34. Two cars start from A and B at the same time, face to face, each lane of A is 50 kilometers, and each lane of B is 60 kilometers, and they meet after 3.5 hours. How many kilometers is it between A and B? (Answer in two ways)
35. Xiaoming and Xiaoqing's homes are 4.5 kilometers apart. They both ride bicycles from home at the same time. Xiaoming travels 50 meters per minute and Xiaoqing travels 40 meters per minute. How many minutes did they meet?
36. Xiaoming and Xiaoqing's homes are 4.5 kilometers apart. They both ride bicycles from home at the same time. Xiaoming travels 50 meters per minute and Xiaoqing travels 40 meters per minute. How many minutes did they meet?
37. Buses and trucks start from two cities at the same time and go in opposite directions. Buses travel 45 kilometers per hour, 3 kilometers more than trucks. Four hours later, the two cars met. How many kilometers are the two cities apart?
At the same time, two engineering teams opened an 850-meter-long tunnel from both ends. Team A digs 26 meters every day, while Team B digs 24 meters every day. How many days will it take to pass?
6. Master and apprentice work together to process a batch of parts. The master processes 68 parts per hour and the apprentice processes 55 parts per hour. They worked together for six hours to finish the task. How many parts are there in this batch?
7. The processing plant uses two mills to grind 17280 kg at the same time. The first grinder grinds 364 kilograms per hour, and the second grinder grinds 356 kilograms per hour. If the flour is processed for 8 hours every day, how many days will it take to finish grinding?
Second, start at the same time and run counter to each other.
1, Party A and Party B start from the school at the same time and go in opposite directions. A walks 60 meters per minute, and B walks 70 meters per minute. How many meters are they apart after 5 minutes? (Answer in two ways)
The first method: the second method:
Two cars start from a factory at the same time and go in opposite directions. One car travels 33 kilometers per hour, and the other car travels 42 kilometers per hour. How many minutes later, the distance between two cars 15km?
Third, start at the same time, move in the opposite direction, and don't meet.
1, the railway between Station A and bilibili is 560 kilometers long. Two trains leave from two stations at the same time. One train runs at 63.5 kilometers per hour, and the other train runs at 80.5 kilometers per hour. How many kilometers are there between the two trains after three hours?
2. The trucks and buses leave from Party A and Party B relatively simultaneously. Trucks travel 57.5 kilometers per hour and buses travel 45.8 kilometers per hour. After 3 hours, the distance between the two cars is 100 km. How many kilometers is the distance between Party A and Party B?
3. Master and apprentice process 3 12 parts at the same time. The master processes 45 parts per hour and the apprentice processes 35 parts per hour. How many hours after processing, there are 40 parts left?
Fourth, don't start at the same time and move in the opposite direction.
1, Train A and Train B travel relatively from two places. Car A is 75 kilometers per hour, and car B is 69 kilometers per hour. A car leaves 1 hour later, B car leaves and meets in 5 hours. How many kilometers is the railway between these two places? (Answer in two ways)
The first method: the second method:
2. The waterway of Port A and Port B is 726 kilometers long. A cargo ship sailed from Port A to Port B at a speed of 69 kilometers per hour. 1 hour later, a passenger ship set sail from port b at a speed of 77 kilometers per hour. How many hours after the passenger ship left, it met the cargo ship? How many kilometers did the passenger ship travel when it met the cargo ship?
3. For a batch of 478 parts, Party A processes 50 parts per hour, while Party B processes 32 parts per hour. Party A processes for 3 hours first, and the remaining two people work together for several hours to complete the task.
5. Same time, same place, same direction.
Both Party A and Party B ride bicycles from A to B at the same time. Party A travels14.2km per hour and Party B travels18.7km per hour. How many kilometers are they apart after 8 hours? (Answer in two ways)
The first method: the second method:
Travel application problem
1. The bus and truck depart from Party A and Party B respectively, with a distance of 387 kilometers. The bus travels 1 hour, traveling 72 kilometers per hour, and meets the bus 2.5 hours after the truck leaves. How many kilometers does this truck travel per hour?
Two cars, A and B, are driving in the same direction at the same time. Car A travels 42 kilometers per hour and car B travels 45 kilometers per hour. How many kilometers are the two cars apart after 2.4 hours?
3. Two ships, Party A and Party B, leave the dock in opposite directions at the same time. Party A travels 23.5km per hour and Party B travels 2 1.5km per hour. After several hours of sailing, the distance between the two ships is 3 15km.
4. Two trains, A and B, leave from two places 453 kilometers apart at the same time. The speed of train A is 45 kilometers per hour. Five hours have passed, and the distance between the two cars is still 28 kilometers. How many kilometers does the second car travel per hour?
A car travels from place A to place B at a speed of 56 kilometers per hour. Three hours later, there are still six kilometers from the midpoint. How many kilometers is the bus from B?
6. Two trains leave from Party A and Party B at the same time. The first train departs from Station A at a speed of 50 kilometers per hour, and the second train departs from bilibili at a speed of 60 kilometers per hour. When the two trains met, the first train had just finished the journey, and there were still 300 kilometers from bilibili ... How many kilometers between A and B?
7. Two students, A and B, are running in the same direction on a 400-meter track. A is 5 meters per second and B is 6 meters per second. They met in a few seconds.
8. Zhao Lan walks to school, walking 75 meters per minute. Six minutes after Zhao Lan left home, her mother found that Zhao Lan was not wearing a red scarf, so she rode a bicycle to catch up and walked 375 meters per minute. A few minutes after Mom left, could she catch up with Zhao Lan?
9. Two cars, A and B, are driving in opposite directions from two places at the same time. A travels 83 kilometers per hour and B travels 95 kilometers per hour. The two cars met at a distance of 24 kilometers from the midpoint. How far is the distance between the two places?
10, the two trains A and B leave from two opposite stations respectively. Train A travels 48 kilometers per hour and train B travels 52 kilometers per hour. If train A travels 20 kilometers less than train B when they meet, what is the distance between the two stations?
1. There are 28 children waiting in line. The number from the left 10 is Aihua. What's the number on his right?
2. new york time is HK time minus 13 hours. You have an appointment with a friend in new york to call him at 8 pm on April 1 new york time. When should you call him in Hong Kong?
A worker can process 90 parts in 5 hours. /kloc-how many workers does it take to process 540 parts in 0/0 hour?
4. How many integers greater than 100 have the same quotient and remainder after dividing by 13?
5. Four rooms, with no less than two people in each room and no less than eight people in any three rooms. How many people are there in these four rooms?
6. The divisor (or factor) of1998 has two digits, which is the largest?
7. In the English exam, Xiao Ming scored an average of 88 points in the first three times. How many points does he get if he wants to average 90 points for the fourth time?
8. There are at most five Sundays in a month. 12 What are the months with five Sundays in a year?
9. Choose six of the ten numbers 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9, and fill in the following boxes to make the formula hold. Each box is filled with a number, and the number in each box is different.
□ +□□ =□□□
What is the largest three digits in the formula?
10. A number is six digits, the first four digits are 2857, and the last two digits are unclear, namely
2857□□
But I remember it can be divisible by 1 1 and 13. Please work out the last two figures.
1 1. A school has 5 18 students. If the number of boys increases by 4% and the number of girls decreases by 3, the total number will increase by 8. So how many more boys than girls?
12. Chen Min wants to go shopping three times. 5 yuan, 2 yuan, 1 yuan, how many coins should I bring * * * so that I don't generate any change below 10 yuan at a time?
(There are only three kinds of coins: 5 yuan, 2 yuan, 1 yuan. )
13. The figure on the right is a graph composed of three semicircles, in which the diameter of the small circle is 8 and the diameter of the middle circle is 12.
14. The kindergarten teacher sent some pictures to Class A, Class B and Class C, and everyone can get 6 pictures. If it is only Grade B, everyone can get 15 pictures. If it is only Grade C, everyone can get 14 pictures. If it is Class A, how many photos can each person get?
15. Two people play a game: take turns to count off, and the count off can only be 1, 2, 3, 4, 5, 6, 7, 8. Add up the figures reported by two people. After the number is reported, the plus sign is 123, and the winner will give priority to the number.
16. The page number of the novel must be printed in the font of 1989. 1 How many times does this number appear in the page number of this book?
What are the last four digits of the sum of 17.23: 3, 33, 333, …, 33…3(23 3s)?
18. Arrange the eight numbers 1, 1, 2, 2, 3, 4, 4 into an eight-digit number, so that there is a number between two 1, two numbers between two 2, three numbers between two 3 and two 4. Then, like this.
19. Take at most a few numbers from the natural number 1, 2, 3, …, 2004, 2005, so that the difference between every two numbers is not equal to 4?
20. There is a six-digit telephone number, in which the three digits on the left are the same, and the three digits on the right are three consecutive natural numbers, and the sum of the six digits is exactly equal to the last two digits. What's the phone number?
2 1. If a is a natural number, prove 10 │ (A2005-A 1949).
22. Give 12 different two-digit numbers, and prove that two numbers can be selected from them, and their difference is a two-digit number composed of two identical numbers.
23. Find the smallest three digits of 2 divided by 3, 3 divided by 5 and 5 divided by 7.
24. Let 2n+ 1 be a prime number, and prove that:12,22, …, n2 is divided by 2n+ 1 to get different remainders.
25. The difference between the sum of squares of prime numbers not less than 5 1 will be divisible by 24.
26. There are two kinds of sugar water, A contains 270g of sugar, 30g of water, B contains 400g of sugar, and water100g. Now we want to get100g of 82.5% sugar water. How many grams should we take from everyone?
27. A container contains 65,438+00 liters of pure alcohol. After pouring out 1 l, fill it with water, then pour out 1 l, and then pour out 1 l. What is the concentration of alcohol solution in the container?
28. A few kilograms of 4% salt water evaporated part of the water and became 10% salt water. After adding 300 grams of 4% salt water, it becomes 6.4% salt water. How many kilograms was the original salt water?
29. It is known that a few grams of brine, after adding a certain amount of water for the first time, the concentration of brine becomes 3%, and after adding the same amount of water for the second time, the concentration of brine becomes 2%. Add the same amount of water for the third time to find the concentration of brine.
30. There are three kinds of brines, A, B and C, which are mixed according to the quantity ratio of A to B of 2: 1 to obtain brines with the concentration of 13%; According to the mass ratio of A to B 1: 2, the brine with the concentration of 14% was obtained; According to the mass ratio of A, B and C 1: 1: 3, the brine with the concentration of 10.2% was obtained. What is the concentration of brine C?